In May 2005 the World Health Assembly approved an innovative
and ambitious revision of the International Health Regulations, known as
IHR(2005), in order to detect and control, in a timely manner, all public
health events that may have a serious international impact. It represents
a dramatic move from administrative notification by Member States (MS)
to the World Health Organization (WHO) of cases of a limited list of diseases
to a systematic analysis of health events of international concern, infectious
or not [1]. The analysis of the public health events will take into account
severity, unexpectedness, potential for international spread, and interference
with international movement of people and goods. National focal points
are to be identified in each MS to interact with WHO. The philosophy behind
the new IHR is to promote early dialogue between MS and WHO, leading to
early mutual risk assessment of events which may not necessarily have to
be notified, depending on the results of the assessment and measures taken.
WHO can also use informal sources to detect earlier events of international
concern and then, together with the national focal point, conduct verification,
risk assessment and implement appropriate measures.

To be successful, IHR(2005) will need to rely on sufficient public health
capacity at all levels within the MS, with a strong core surveillance
function that can be summarised as the efficient management of health
data and response from the first line health practitioner (eg, clinician,
biologist) to local, regional and national public health structures.
The key issues are the capacity and performance of the public health
system and its ability to communicate and interact within its different
sectors and with decision makers in a timely, authoritative and transparent
way [1]. IHR(2005) add challenges and responsibilities for MS that may
need to adjust their national public health infrastructure, often without
the help of extra resources. Several events in recent years, such as
SARS, avian influenza and the threat of bioterrorism, have served as
an early introduction to the concept of IHR(2005). The experience of
implementing a weekly early warning committee at the National Institute
for Public Health and the Environment in the Netherlands [2] illustrates
how some MS are already organised in this respect. The European Early
Warning and Response System (EWRS) which has linked MS and the European
Commission through an electronic real time secured system since 1998
(and the European Centre for Disease Prevention and Control since 2005)
has shown added European value for sharing early validated information
on health threats between national public health institutes and authorities
and is certainly an experience that can and will be built on [3].

While IHR(2005) were being developed, there was growing interest and
investment in real time monitoring of health ‘signals’ from
every possible source, including symptoms, syndromes, crude mortality,
drug sales, rumours and media reports. The assumption, which has probably
not been sufficiently challenged from a research perspective, is that
by using rapidly available but less specific information through automated
systems, health threats of the future will (or may) be detected earlier
[4]. Although the debate on ‘non-specific surveillance’ is
not new, there are at least two reasons for this development: the information
technology now available allows real time technical access to health
related databases; and fears about emerging infections and bioterrorism
have created social and political demand for faster and more sensitive
health information systems.

Indeed, media reports have proven helpful for bringing to light undetected
and/or uncontrolled serious outbreaks of international potential, such
as SARS [4]. But can we be sure that media reports will detect a future
emerging epidemic as effectively, and should we consider media reports
as important as the signals generated by surveillance systems? We should
recognise that many large or diffuse outbreaks in the recent past have
not been detected more quickly because of media reports. However, the
way in which the media report a health event or outbreak does give other
important and useful information, particularly on its social and political
perception. This added social dimension is argument enough for the integration
of media monitoring into surveillance schemes.

Three papers [5-7] in this issue of Eurosurveillance report the recent
implementation of non-specific surveillance schemes designed for the
early detection of health threats. All conclude that the systems were
helpful because they were able either to accurately reproduce data
generated by existing specific systems or to document excess mortality
following an already identified risk. However, none demonstrated a
real added capacity to detect events that would otherwise have been
missed! In France, real time syndromic surveillance by emergency departments
was able to track seasonal influenza as successfully as a network of
sentinel general practitioners. It also provided early estimates of
the health impact of the July 2006 heat wave [5]. Real time monitoring
of the number of deaths also documented a moderate increase of crude
mortality during the April 2005 flu outbreak, and of the 2006 heat
wave [5]. In order to detect bioterrorist attacks early in the United
Kingdom, data on 11 key symptoms/syndromes are received electronically
from all National Health System direct call centres covering England
and Wales and analysed using automated detection statistical algorithms
[6]. The system has indicated many sudden rises in syndromes but their
careful analysis has found no evidence of a biological or chemical
attack. The system is most suited to detect widespread rises in syndromes
in the community, but is currently unlikely to detect more localised
outbreaks, such as a cryptosporidiosis outbreak [8]. As shown in France,
the benefits were early tracking of rises of community morbidity of
already identified risks (eg, influenza-like illness, heat-related
deaths following the July 2006 heat wave). It also provided a social
added value by reassuring decision makers that widespread disease was
not occurring, despite a perceived high health risk [6]. Denmark, with
similar goals to the UK, applies a detection algorithm on ambulance
dispatch data [7]. The system can implement reactive symptom surveillance
in case of an alert. Its evaluation found that decreasing the outbreak
detection sensitivity reduced the time to detection moderately, but
diminished the number of false alerts considerably. Although the system
was able to detect an increased activity related to seasonal influenza
in a timely fashion, the authors recognised that small outbreaks occurring
over a number of weeks, like the American anthrax outbreak in 2001,
would be difficult to detect with ambulance dispatch surveillance.

Enhanced surveillance at mass gatherings has previously been conducted
on many occasions [9,10]. Although syndrome based surveillance has been
undertaken at several previous mass gatherings, it is not clear whether,
for regions with a well-functioning surveillance system, it actually
provides more information than that identified through the strengthening
of routine surveillance [9]. After careful consideration of the available
evidence and consultation with state health departments, the Robert Koch-Institute
concluded that enhancing the German mandatory notification surveillance
system would be sufficient for the 2006 World Cup in Germany [9] and
decided not to implement syndrome based surveillance. Their experience
shows that enhancing the existing system accelerated data transmission
and intensified communication and action-orientated cooperation between
players of the German public health system. Enhancing surveillance at
mass gatherings is, certainly a valuable and cost effective communication
and networking exercise of public health structures to face future critical
health-related events [8]. An enhanced, but more intensive system than
the German example given above was set up in the French region of Hautes-Alpes
near the Italian border for the 2006 Olympic Winter Games in Torino
[10]. As in Italy, and in most similar experiences previously, it detected
no particular health events of high public health concern.
Notification of unusual health events from daily healthcare practice
(eg, clinicians, microbiologists, emergency services, hospitals) to public
health structures is a valid source of hazard or outbreak detection if
the capacity for verification and analysis of the public health system
is timely and efficient. Event notification that complements surveillance
activities in an effective way is much more likely to work if there is
a proactive networking activity of health professionals by those who
run the surveillance and public health system. Without a mutual understanding
of the usefulness and public health added value of notification and interactive
communication between healthcare professionals (in particular clinicians
and microbiologists) and public health structures, the challenges and
the high social expectations of health security will not easily be met
and no automated data collection system will be able to replace it. In
this context, the paper by Paquet et al [4] presents an integrated management
model of sources of information with a filtering process, with risk assessment
linked to decision making and action.

Based on the recent scientific literature and the papers published in
this issue, there is a need for more evidence-based research on the performance,
management, effectiveness, cost-effectiveness and added value of non-specific
surveillance and new sources of health signals. This is important given
the cost of implementation and the concurrent needs for disease specific
surveillance and other, equally important, public health programmes such
as prevention or health promotion. Recent experience has shown that a
strong laboratory capacity is necessary at all stages of diagnosis, surveillance
and signal assessment and should, therefore, be more clearly integrated
and supported. Modelling the spread of a new or epidemic infectious disease,
based on available data and reasonable scenarios, is another key element
of risk assessment, particularly at national and supranational levels,
and should be developed further. Some generic activities such as epidemic
intelligence that searches for international health signals would gain
in cost-effectiveness if developed and pooled at European level. All
of the ‘emerging’ tools discussed in this issue are of potential
interest and may be considered by national authorities to complement
gaps in existing national systems based on priority, public health needs
and the requirements of IHR(2005). However, their effectiveness cannot
be assumed without thorough analysis.

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